[ 1212.990408][T11125] Could not find device with ifindex 2000 in netnsfd 11 [ 1212.991131][T11125] Could not find netns with fd: 2000 [ 1212.991676][T11125] Cannot link a netdevsim to itself [ 1212.992337][T11125] Format for linking two devices is "netnsfd_a:ifidx_a netnsfd_b:ifidx_b" (int uint int uint).